“Soul mate” is a tricky term because technically speaking it's not a one-on-one exclusive. By definition souls transcend bodies which means that your soul could potentially mate with just about anyone's on the planet. It's our bodies that are bound to each other through our attractions, wants, and needs, not our souls. Now this may sound like metaphysical hair-splitting, but it explains why you keep searching without really finding. Universal experiences don't really lend themselves to intimate relationships. Try being less out-of-body in your approach and more down-to-earth during the time that the Sun is in Cancer and you may discover what you're looking for.